Performance Characteristics Of An Intensity Modulated Advanced X-Ray Source (IMAXS) For Homeland Security Applications

Langeveld, W. G.J.; Brown, C.; Christensen, Phil. A.; Condron, Cathie L.; Hernández, Michael; Ingle, Mike; Johnson, William A.; Owen, Roger DeBaun; Ross, R.; Schonberg, R. G.

doi:10.1063/1.3586194

Cited by 5 publications

(3 citation statements)

References 1 publication

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“…The second option requires an octupole corrector magnet placed before the quadrupole to generate a nonlinear compensating effect on the vertical beam orbit (~y 3 ). In this case, the field strengths of neither the octupole nor the quadrupole depend on beam angle at the target, but they must be switched to either 6 MeV or 10 MeV values (proportional to the beam energy) on the ~1 kHz time scale.…”

Section: Vertical Intensity Modulation (Vim)mentioning

confidence: 99%

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Vertical intensity modulation for improved radiographic penetration and reduced exclusion zone

Bendahán¹,

Langeveld²,

Bharadwaj

et al. 2016

Int. J. Mod. Phys. Conf. Ser.

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In the present work, a method to direct the X-ray beam in real time to the desired locations in the cargo to increase penetration and reduce exclusion zone is presented. Cargo scanners employ high energy X-rays to produce radiographic images of the cargo. Most new scanners employ dualenergy to produce, in addition to attenuation maps, atomic number information in order to facilitate the detection of contraband. The electron beam producing the bremsstrahlung X-ray beam is usually directed approximately to the center of the container, concentrating the highest Xray intensity to that area. Other parts of the container are exposed to lower radiation levels due to the large drop-off of the bremsstrahlung radiation intensity as a function of angle, especially for high energies (>6 MV). This results in lower penetration in these areas, requiring higher power sources that increase the dose and exclusion zone. The capability to modulate the X-ray source intensity on a pulse-by-pulse basis to deliver only as much radiation as required to the cargo has been reported previously. This method is, however, controlled by the most attenuating part of the inspected slice, resulting in excessive radiation to other areas of the cargo. A method to direct a dual-energy beam has been developed to provide a more precisely controlled level of required radiation to highly attenuating areas. The present method is based on steering the dual-energy electron beam using magnetic components on a pulse-to-pulse basis to a fixed location on the Xray production target, but incident at different angles so as to direct the maximum intensity of the produced bremsstrahlung to the desired locations. The details of the technique and subsystem and simulation results are presented.

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Section: Vertical Intensity Modulation (Vim)mentioning

confidence: 99%

“…1,2,3 Here, the X-ray source intensity is adjusted based on the maximum attenuation of the previous slice. Electronics in the detector array detects the maximum attenuation within the slice and sends commands to the source to change the intensity to an appropriate value.…”

Section: Introductionmentioning

confidence: 99%

Vertical intensity modulation for improved radiographic penetration and reduced exclusion zone

Bendahán¹,

Langeveld²,

Bharadwaj

et al. 2016

Int. J. Mod. Phys. Conf. Ser.

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“…The electrons interact with the electrostatic field of the tungsten atoms becoming deflected and losing energy in the form of an x ray. Linear accelerators produce pulses of electrons and, therefore, pulses of x rays, with each pulse duration of the order of 1 μs (see (Langeveld, et al, 2011) for an example of a linear accelerator with a 0.1 to 4.7 μs variable pulse width). The electrons are accelerated inside the accelerator using a potential difference typically set to 4, 6, or 9 MV for cargo imaging.…”

Section: Current Cargo Screening Techniquesmentioning

confidence: 99%

Preliminary Monte Carlo simulations of linear accelerators in Time-of-Flight Compton Scatter imaging for cargo security

Calvert

Morton²,

Speller

2013

Crime Sci

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The economic impact of illicit trade is in the trillions of dollars per year, with a proportion of this trade concealed within cargo containers. The interdiction of this trade relies upon efficient and effective external screening of cargo containers, typically using x rays. The present work introduces a technique of x-ray screening that aims to increase the efficiency and effectiveness of x-ray screening. Traditional X-ray screening of cargo containers is performed using high-energy (MV) transmission imaging or low-energy (kV) Compton scatter imaging to provide two-dimensional images. Two-dimensional images can contain complex, overlapping objects and require significant experience and time to interpret. Time-of-Flight information can be used in conjunction with Compton scatter imaging to provide information about the depth of each Compton scatter interaction, leading to three-dimensional images, reducing false positives and image analysis time. The expected Time-of-Flight from photons scattered back from a set of objects is well defined when the photons are produced with a delta-type (infinitely narrow) pulse duration, however, commercially available linear accelerators used for cargo screening typically have pulse widths of the order of 1 μs. In the present work, the possible use of linear accelerators for Time-of-Flight Compton scatter imaging is investigated using a mixture of analytic and Monte Carlo methods. Ideal data are obtained by convolving a number of wide x-ray pulses (up to 5 μs) with the expected Time-of-Flight from a set of objects using a delta-type pulse. Monte Carlo simulations, using Geant4, have been performed to generate x-ray spectra produced by a linear accelerator. The spectra are then used as the input for detailed Monte Carlo simulations of the Time-of-Flight of photons produced by a single linear accelerator pulse scattering back from a set of objects. Both ideal and Monte Carlo data suggest that Time-of-Flight information can be recovered from a wide linear accelerator pulse, provided that the leading and falling edge of the pulse are sharp. In addition, it has been found that using a linear accelerator leads to double the amount of Time-of-Flight information as both the leading and falling edge are utilised (unlike for a delta-type pulse).

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Review of active interrogation techniques

Bendahán¹

2020

Nuclear Instruments and Methods in Physics Research Section A:

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Performance Characteristics Of An Intensity Modulated Advanced X-Ray Source (IMAXS) For Homeland Security Applications

Cited by 5 publications

References 1 publication

Vertical intensity modulation for improved radiographic penetration and reduced exclusion zone

Vertical intensity modulation for improved radiographic penetration and reduced exclusion zone

Preliminary Monte Carlo simulations of linear accelerators in Time-of-Flight Compton Scatter imaging for cargo security

Review of active interrogation techniques

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